1. Field of the Invention
This apparatus relates to exercise apparatus and particularly to apparatus for rowing exercises.
2. Prior Art
There are three properties that determine the value of an exercise apparatus:
1. The ability of the apparatus to isolate on a muscle group.
2. The number of muscle groups for which the apparatus can be used.
3. The range of resistance that the apparatus provides.
There are many kinds of rowing machines on the market. One common structural characteristic of these machines is that a seat is provided which rolls on a track. A slanted platform is attached at one end of the track onto which the user places his feet. Handles are provided which the user moves against resistance by straightening his hips, knees and pulling with his arms and shoulders. There are a number of approaches to providing resistance to movement of the handles. According to one design, oars (or fulcrum bars) are attached at fixed fulcrum point attached to each side of the track. A hydraulic ram is attached between a position on the oar and a point on the track near the feet. In another design, the handles are attached to cables leading to springs which are stretched by the rowing movement.
In the exercise of rowing, the user uses muscles of the upper and lower back, the buttocks, the quads, the hamstrings, Since all of these muscle groups are functioning simultaneously, rowing is excellent for conditioning the cardiovaxcular system. However, it is not satisfactory for isolation on a particular muscle group therefore the rowing machines that are presently available are not good "strength" building machines for any of the fore named muscle groups.
Furthermore, there is no means of adjusting the distribution of resistance between the various muscle groups to accomodate the fact that individuals vary with regard to their need or desire to exert upper body force versus lower body force. For example, the ratio of upper body strength to lower body strength is greater for men than it is for women.
Another deficiency with regard to current rowing machines is that the method of applying resistance provides a limited range. When one considers that muscle groups in some ranges of motion require resistances of several hundred pounds whereas other muscle groups require less than 100 pounds, it is apparent that rowing machines currently available are inadequate with respect to available resistance ranges.
In rowing machines of the prior art, resistance is presented to motion of a plunger in the cylinder of a ram by flow of oil through a passage from one side of the plunger to the other side. Variation of resistance is acheived by changing the point of attachment of the ram to the oar. But this design severely limits the resistance presented to straightening the knees and thereby puts most of the stress on the hips and back. Another limitation of this is design is the small range of motion provided.